1. Field of the Invention
The present invention generally relates to communication systems, and more particularly, to a system and method for communicating in a point-to-multipoint digital subscriber line (DSL) network.
2. Discussion of the Related Art
In recent years, telephone communication systems have expanded from traditional plain old telephone system (POTS) communications to include high-speed data communications as well. As is known, POTS communications include the transmission of voice information, as well as PSTN (public switched telephone network) modem information, control signals, and other information that is transmitted in the POTS bandwidth.
Prompted largely by the growth in Internet usage, the provision of xDSL services to customer premises has proliferated over recent years. In this regard, the descriptor “x” preceding the DSL designator is used to broadly denote a variety of DSL services, including ADSL, RADSL, HDSL, etc. As is known, xDSL transmissions are sent to customer premises over the same twisted pair cabling as POTS transmission are sent.
Since xDSL transmissions are communicated in a frequency band that is separate and distinct from the POTS frequency band, transmitting both types of signals over the same cabling (even at the same time), generally is not a problem. Specifically, the POTS frequency band is defined between approximately DC and approximately 4 kHz, while xDSL frequency bands (although they vary depending upon the specific service) are generally defined by a lower cutoff frequency of approximately 26 kHz, and an upper cutoff frequency that depends upon the particular xDSL service. As will be used hereinafter, the term DSL will be used interchangeably with the term xDSL, and should be construed to generically reference any of the of the various DSL services.
As is known, DSL is an additional service the customer typically purchases from its local service provider. The local service provider typically charges an additional service charge for the provision of the service. Until recently, the additional service charges have been somewhat substantial, resulting in a general limitation of the service to business enterprises. However, the services are now becoming more affordable, and therefore in higher demand. For many individuals, households, and even small businesses, installation charges have often provided a “barrier to entry,” in the past. However, with the development of standards like G.Lite, certain equipment requirements (e.g., pots splitters at the customer premises) have been eliminated, and therefore installation costs reduced.
Local area networks (LANs) have also helped reduce the “effective cost” of DSL services. In this regard, many small businesses (and even homes with multiple computers) implement LANs over which multiple computers can inter-communicate. In a LAN environment, a single DSL service/connection may be purchased and configured to allow all computers on the LAN to have access to the DSL service, and therefore access to the Internet or other wide area network (WAN). Although such computer configurations have increased the demand for DSL services, and effectively lowered the per computer cost for the DSL service, certain shortcomings exist, precipitating the desire for improvements in these systems.
To better illustrate, reference is made to FIG. 1, which is a block diagram illustrating a typical LAN configured for connection to a WAN. A typical LAN 10 may have a plurality of computers 12, 14, 16, and 18 interconnected for inter-communication. To enable this communication across the LAN 10, each computer typically contains a LAN card 13, 15, 17, in 19. As is well known, a LAN card provides the facilities in the lower-level's of the OSI model, to enable the computers to inter-communicate. Additional facilities and capabilities, however, are conventionally required in order for the computers to communicate over a WAN. These additional facilities are provided by way of a WAN card 20. As is known, a WAN card provides similar functionality to a. LAN card, but the voltage levels, protocols, and modulation schemes for communicating over a WAN are different than those for communicating over a LAN. Accordingly the hardware associated with the transmission in reception of signals over a WAN versus signals over a LAN are different, and therefore different hardware is required.
In a typical configuration, however, only a single WAN card 20 is required. A single DSL service may be purchased and configured between the wide area network and the computer 12 having the WAN card 20. Nevertheless, communications from other computers, such as computer 14, 16, or 18, may be made over the WAN. For example, if computer 14 desires an Internet connection, this connection may be established and maintained for the combination of communications between computer 14 and computer 12 over the LAN, then computer 12 to the WAN, via the DSL service. As is also known, each computer in the LAN may be uniquely identified by an IP address, and this IP address may be used to direct and channel communications between the WAN and a respective computer. Alternatively, computer 12 may be the only computer configured with an IP (Internet Protocol) address, and the remaining computers 14, 16, and 18 may be identified by sub-IP addresses, making them “invisible” to the WAN, but readily identifiable by computer 12, or other computers on the LAN. Using protocols such as TCP/IP this communication flow may be established and maintained, in ways are well-known to persons of ordinary skill in the art, and therefore need not be described herein.
While a system, like the one broadly illustrated in FIG. 1, provides effective means for reducing the per computer cost of a DSL connection/service, there are nevertheless certain shortcomings in this system configuration. For example, this configuration is characterized by a single point of failure. Specifically, if the computer 12 having the WAN card 20 is shut down, otherwise fails, then the remaining computers 14, 16, and 18 on the LAN 10 lose their ability to communicate over the WAN. Another problem relates to configurability and user-friendliness of the system. Particularly for home environments, and small business enterprises, which cannot readily afford a computer specialist, simplicity in system configuration and implementation is an important factor. It should be appreciated that the system in FIG. 1 requires a certain level of sophistication in installing and configuring the computer 12 having the WAN card. Further, if operational problems arise, then troubleshooting such a system requires a certain level of user sophistication.
Accordingly, it is desired to provide a networked computer system having the single DSL connection/service benefits of the system FIG. 1, but providing greater simplicity and user-friendliness from the end-user perspective.